Semiconductor-on-diamond devices and methods of forming

ABSTRACT

The present invention provides semiconductor-on-diamond devices, and methods for the formation thereof. In one aspect, a mold is provided which has an interface surface configured to inversely match a configuration intended for the device surface of a diamond layer. An adynamic diamond layer is then deposited upon the diamond interface surface of the mold, and a substrate is joined to the growth surface of the adynamic diamond layer. At least a portion of the mold can then be removed to expose the device surface of the diamond which has received a shape which inversely corresponds to the configuration of the mold&#39;s diamond interface surface. The mold can be formed of a suitable semiconductor material which is thinned to produce a final device. Optionally, a semiconductor material can be coupled to the diamond layer subsequent to removal of the mold.

PRIORITY DATA

[0001] This application is a continuation-in-part of U.S. patentapplication Ser. No. 10/421,369,filed on Apr. 22, 2003, which isincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

[0002] The present invention relates to semiconductor devicesincorporating super-hard materials, such as diamond or diamond-likesubstances, and methods for making such devices. More particularly, thepresent invention relates to the use of vapor deposition for makingsemiconductor devices incorporating diamond materials.

BACKGROUND OF THE INVENTION

[0003] Diamond and diamond-like substances have many properties, such aswear resistance, thermal conductivity, electrical resistivity, acoustictransmission, and corrosion inertness, which make them desirable for avariety of industrial applications. To this end, diamond anddiamond-like substances have been incorporated into tools for variouspurposes such as saw blades, drill bits, and electronic components suchas surface acoustic wave filters. Methods for incorporating diamond ordiamond-like materials into a tool can include known processes such aschemical vapor deposition (CVD) and physical vapor deposition (PVD).

[0004] Various CVD techniques have been used in connection withdepositing diamond or diamond-like materials onto a substrate. TypicalCVD techniques use gas reactants to deposit the diamond or diamond-likematerial in a layer, or film. These gases generally include a smallamount (i.e. less than about 5%) of a carbonaceous material, such asmethane, diluted in hydrogen. A variety of specific CVD processes,including equipment and conditions, are well known to those skilled inthe art.

[0005] In forming a layer of diamond, or diamond-like material on asubstrate using CVD techniques, a plurality of diamond grains, or“seeds,” may be first placed upon the substrate surface. The placementof such seeds may be accomplished using CVD itself such as by applying avoltage bias, by polishing with micron-sized diamond, or by othermethods known in the art. These seeds act as diamond nuclei andfacilitate the growth of a diamond layer outwardly from the substrate ascarbon vapor is deposited thereon. As a result, the growing side of thediamond layer becomes increasingly coarse in grain size, and mustultimately be ground and polished to a smooth finish such as by amechanical means, in order to be suitable for many industrialapplications. However, as diamond and diamond-like substances are amongthe hardest known materials, such mechanical grinding and polishing isdifficult and tedious. Moreover, the cost of polishing often exceeds thecost for making the diamond film itself. In addition, mechanicalpolishing inevitably introduces micro-cracks or variations on thediamond surface. Such cracks and variations are detrimental to certainapplications.

[0006] The semiconductor industry has recently expanded efforts inproducing semiconductor-on-insulator (SOI) devices. These devices allowfor electrical insulation between an underlying substrate and any numberof useful semiconductor devices. Typically, these SOI devices caninclude insulating layers with poor thermal conductivity, high degree ofthermal expansion mismatch, and/or difficulties in epitaxial growth ofsilicon or other semiconductor materials. In light of some of thesedifficulties, various efforts have explored using diamond as theinsulating layer with some success. However, such devices continue tobenefit from further improvement such as decreasing manufacturing costs,improving performance, and the like.

[0007] As such, SOI devices and methods for making diamond containingSOI devices which have improved performance and reduced production costscontinues to be sought.

SUMMARY OF THE INVENTION

[0008] Accordingly, the present invention providessemiconductor-on-diamond (SOD) devices and methods for making suchdevices that address many of the difficulties mentioned above. As such,the present devices and methods are capable of providing SOD deviceswith improved insulating properties and which are particularly suitablefor use in insulating semiconductor devices and the like.

[0009] In one aspect of the present invention, a SOD device can includea substrate having an adynamic diamond layer on the substrate. A devicesurface of the adynamic layer can be oriented distal to the substrate.Further, a semiconductor layer can be coupled to the device surface ofthe diamond layer. The semiconductor layer can be formed directly on theintermediate layer or formed on an intermediate layer.

[0010] In an additional aspect, the semiconductor layer can be coupledusing an intermediate layer such as aluminum nitride, chromium nitride,silicon, silicon carbide, silicon nitride, tungsten carbide, galliumnitride, diamond-like carbon, and composites thereof.

[0011] In one detailed aspect, the device surface can have a surfaceroughness (Ra) from about 1 nm to about 1 μm.

[0012] As a general matter, the method of making an SOD device inaccordance with the present invention begins by providing a mold havingan interface surface configured to inversely match a configurationintended for a device surface of the diamond SOD device. An adynamicdiamond layer can then be grown on the diamond interface surface of themold using a vapor deposition technique. As diamond growth proceeds, theadynamic diamond layer receives a growth surface opposite the devicesurface, which is then joined to a substrate or support layer. Asemiconductor layer can also be coupled to the device surface.

[0013] In one embodiment, at least a portion of the mold can be removed.In some cases, the mold can be thinned to form either the semiconductorlayer and/or the intermediate layer. Thus, the mold can be chosen of amaterial suitable for incorporation into the final SOD device.Alternatively, the mold can be completely removed and a semiconductorlayer, and optional intermediate layer, formed on the exposed diamonddevice surface.

[0014] In still another alternative aspect, a method of making a SODdevice can include providing a mold having an interface surface. Anadynamic diamond layer can be grown on the interface surface using avapor deposition technique, said adynamic diamond layer having a growthsurface opposite the interface surface. A semiconductor layer can alsobe coupled to the growth surface of the adynamic diamond layer.

[0015] There has thus been outlined, rather broadly, the more importantfeatures of the invention so that the detailed description thereof thatfollows may be better understood, and so that the present contributionto the art may be better appreciated. Other features of the presentinvention will become clearer from the following detailed description ofthe invention, taken with the accompanying drawings and claims, or maybe learned by the practice of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0016]FIG. 1 is a side cross-sectional view of an SOD device inaccordance with an embodiment of the present invention.

[0017]FIG. 2 is a side cross-sectional view of an SOD device inaccordance with an alternative embodiment of the present invention.

[0018]FIGS. 3A through 3D show side cross-sectional views illustratingone method of producing SOD devices in accordance with the presentinvention.

[0019]FIGS. 4A through 4C show side cross-sectional views illustratingan alternative method of producing SOD devices in accordance with thepresent invention.

[0020] The above figures are provided for illustrative purposes only. Itshould be noted that actual dimensions of layers and features may differfrom those shown.

DETAILED DESCRIPTION

[0021] Before the present invention is disclosed and described, it is tobe understood that this invention is not limited to the particularstructures, process steps, or materials disclosed herein, but isextended to equivalents thereof as would be recognized by thoseordinarily skilled in the relevant arts. It should also be understoodthat terminology employed herein is used for the purpose of describingparticular embodiments only and is not intended to be limiting.

[0022] It must be noted that, as used in this specification and theappended claims, the singular forms “a,” and, “the” include pluralreferents unless the context clearly dictates otherwise. Thus, forexample, reference to “an intermediate layer” includes one or more ofsuch layers, reference to “a carbon source” includes reference to one ormore of such carbon sources, and reference to “a CVD technique” includesreference to one or more of such CVD techniques.

[0023] Definitions

[0024] In describing and claiming the present invention, the followingterminology will be used in accordance with the definitions set forthbelow.

[0025] As used herein, “super hard” and “superabrasive” may be usedinterchangeably, and refer to any crystalline, or polycrystallinematerial, or mixture of such materials which has a Moh's hardness ofabout 8 or greater. In some aspects, the Moh's hardness may be about 9.5or greater. Such materials include but are not limited to diamond,polycrystalline diamond (PCD), cubic boron nitride, polycrystallinecubic boron nitride (PCBN) as well as other super hard materials knownto those skilled in the art. Super hard materials may be incorporatedinto the present invention in a variety of forms including particles,grits, films, layers, etc.

[0026] As used herein, “substrate” refers to a non-diamond surface, towhich various materials can be joined in forming an SOD device. Thesubstrate may be any shape, thickness, or material, required in order toachieve a specific result, and includes but is not limited to metals,alloys, ceramics, and mixtures thereof. Further, in some aspects, thesubstrate, may be an existing semiconductor device or wafer, or may be amaterial which is capable of being joined to a suitable device. In someadditional aspects, the substrate can be a material that once bonded toan adynamic diamond layer, has sufficient integrity to prevent the layerfrom changing shape once separated from the mold upon which it was made.

[0027] As used herein, “metallic” refers to any type of material orcompound wherein the majority portion of the material is a metal. Assuch, various oxide, nitride, and carbide compounds, as well as anyother material or compound, containing a greater non-metal portion thanmetal portion are not considered to be “non-metallic.” Examples ofvarious metals considered to be particularly useful in the practice ofthe present invention include, without limitation: aluminum, tungsten,molybdenum, tantalum, zirconium, vanadium, chromium, copper, and alloysthereof.

[0028] As used herein, “ceramic” refers to a non-diamond, non-metallic,material, which is hard, heat resistant, corrosion resistant, and can bepolished to have a surface roughness (Ra) of less than about 1micrometer. Further, as used herein, “ceramic” materials may contain atleast one element selected from the group consisting of: Al, Si, Li, Zn,and Ga. Oxides, nitrides, and various other compounds which include theabove recited elements are well known as ceramics to those skilled inthe art. Additional materials considered to be “ceramics” as usedherein, such as glass, are known to those skilled in the art. Examplesof specific ceramics useful in the present invention include withoutlimitation, Si, SiO₂, Si₃N₄, Al₂O₃, AlN, BN, TiN, ZrN, GaAs, GaP,LiTaO₃, LiNbO₃, ZnO, glass, such as soda glass, etc.

[0029] As used herein, “interface surface” refers to the surface of amold, or ephemeral mold, or other layer of material conveying the shapeof the mold, upon which materials used in the fabrication of a diamondlayer or film are deposited. Such materials include diamond or othersuperabrasive particles, as well as peripheral materials used tofacilitate diamond layer growth using a CVD technique, such as diamondnucleation enhancers. The interface surface can be the immediate surfaceof the mold or may include an exposed surface resulting from a thinlayer of material formed thereon which does not significantly affect thesurface contours and roughness of the original mold surface, and thusconveys the configuration thereof. Such thin layers can includenucleation enhancing materials, piezoelectric materials, and any othermaterial which can be formed in sufficiently thin layers so as to retaina substantially identical surface as the original smooth mold surface.

[0030] As used herein with respect to a mold, “outside surface” refersto a surface of the mold which is not in direct contact with the diamondlayer.

[0031] As used herein, “adynamic” refers to a type of layer which isunable to independently retain its shape and/or strength. For example,in the absence of a mold or support layer, an adynamic diamond layerwill tend to curl or otherwise deform when the mold or support surfaceis removed. While a number of reasons may contribute to the adynamicproperties of a layer, in one aspect, the reason can be the extremethinness of the layer.

[0032] As used herein, “nucleation enhancer” refers to a material, whichincreases the quality of a diamond layer formed from a plurality ofdiamond nuclei using a CVD process. In one aspect, the nucleationenhancer may increase the quality of the diamond layer by reducingmovement or, or immobilizing diamond nuclei. Examples of nucleationenhancers include without limitation, metals, and various metalliccompounds, as well as carbides and carbide forming materials.

[0033] As used herein with respect to a nucleation enhancer layer and anintermediate layer, “thin” refers to the thickness or depth of the layerbeing sufficiently small so as to not substantially interfere with thetransfer of the intended configuration from the interface surfaceconfiguration to the device surface. In one aspect, the thickness of thenucleation enhancer may be less than about 0.1 micrometers. In anotheraspect, the thickness may be less than 10 nanometers. In another aspect,the thickness may be less than about 5 nanometers.

[0034] As used herein, “device surface” refers to the surface of adiamond layer which contacts a semiconductor or other electronic device.

[0035] As used herein, “diamond layer” refers to any structure,regardless of shape, which contains diamond-containing materials whichcan be incorporated into a SOD device. Thus, for example, a diamond filmpartially or entirely covering a surface is included within the meaningof these terms. Additionally, a layer of a material, such as metals,acrylics, or composites, having diamond particles disbursed therein isincluded in these terms.

[0036] As used herein, “diamond-containing materials” refer to any of anumber of materials which include carbon atoms bonded with at least aportion of the carbons bonded in at least some s bonding.Diamond-containing materials can include, but are not limited to,natural or synthetic diamond, polycrystalline diamond, diamond-likecarbon, amorphous diamond, and the like. Most often, the diamond layersof the present invention are formed as diamond-like carbon and/oramorphous diamond.

[0037] As used herein, “vapor deposited” refers to materials which areformed using vapor deposition techniques.

[0038] As used herein, “vapor deposition” refers to a process ofdepositing materials on a substrate through the vapor phase. Vapordeposition processes can include any process such as, but not limitedto, chemical vapor deposition (CVD) and physical vapor deposition (PVD).A wide variety of variations of each vapor deposition method can beperformed by those skilled in the art. Examples of vapor depositionmethods include hot filament CVD, rf-CVD, laser CVD (LCVD),metal-organic CVD (MOCVD), sputtering, thermal evaporation PVD, ionizedmetal PVD (IMPVD), electron beam PVD (EBPVD), reactive PVD, and thelike.

[0039] As used herein, “chemical vapor deposition,” or “CVD” refers toany method of chemically depositing diamond or other particles in avapor form upon a surface. Various CVD techniques are well known in theart.

[0040] As used herein, “CVD passive material” refers to a material whichdoes not allow substantial deposition of diamond or other materialsusing CVD methods directly to the material. One example of a CVD passivematerial with respect to deposition of diamond is copper. As such,during CVD processes carbon will not deposit on the copper but only onCVD active materials such as silicon, diamond, or other known materials.Thus, CVD passive materials can be “passive” with respect to somematerials and not others. For example, a number of carbide formers canbe successfully deposited onto copper.

[0041] As used herein, “inversely correspond” refers to the inverserelationship between the configuration of a diamond device surface, andthe configuration of a mold's interface surface from which the devicesurface was made, when such surfaces are oriented in the same direction.In other words, when a device surface is formed at the interface surfaceof a mold, the configuration of each will inversely correspond to theother when the surfaces are separated and faced in the same direction.In some instances, the inverse correspondence may result in a mirrorimage.

[0042] As used herein, “nucleation side,” “nucleation surface,” andsimilar terms may be used interchangeably, and refer to the side orsurface of a diamond layer at which nucleation of diamond particlesoriginated. Otherwise described, the nucleation surface of a diamondlayer is the side or surface, which was first deposited upon theinterface surface of a mold. In many instances, the nucleation surfacemay become the device surface of the tool.

[0043] As used herein, “growth side,” “grown side,” and “grown surface”may be used interchangeably and refer to the surface of a superabrasivefilm or layer which is grows during a CVD process.

[0044] As used herein, “Ra” refers to a measure of the roughness of asurface as determined by the difference in height between a peak and aneighboring valley. Further, “Rmax” is a measure of surface roughness asdetermined by the difference in height between the highest peak on thesurface and the lowest valley on the surface.

[0045] As used herein with respect to an identified property orcircumstance, “substantially” refers to a degree of deviation that issufficiently small so as to not measurably detract from the identifiedproperty or circumstance. The exact degree of deviation allowable may insome cases depend on the specific context. Thus, for example, a sourcematerial which has a composition “substantially” that of a particularregion may deviate in composition or relevant property by experimentalerror up to several percent, e.g., 1% to 3%.

[0046] Concentrations, amounts, and other numerical data may beexpressed or presented herein in a range format. It is to be understoodthat such a range format is used merely for convenience and brevity andthus should be interpreted flexibly to include not only the numericalvalues explicitly recited as the limits of the range, but also toinclude all the individual numerical values or sub-ranges encompassedwithin that range as if each numerical value and sub-range is explicitlyrecited.

[0047] As an illustration, a numerical range of “about 1 micrometer toabout 5 micrometers” should be interpreted to include not only theexplicitly recited values of about 1 micrometer to about 5 micrometers,but also include individual values and sub-ranges within the indicatedrange. Thus, included in this numerical range are individual values suchas 2, 3, and 4 and sub-ranges such as from 1-3, from 2-4, and from 3-5,etc.

[0048] This same principle applies to ranges reciting only one numericalvalue. For example, a range recited as “less than about 5 micrometers”should be interpreted to include all values and sub-ranges between 5micrometers and 0 micrometers, including the value of 0 micrometers.Furthermore, such an interpretation should apply regardless of thebreadth of the range or the characteristics being described.

[0049] The Invention

[0050] Referring now to FIG. 1, a semiconductor-on-insulator (SOI)device is shown generally at 200 in accordance with one embodiment ofthe present invention. A substrate 202 can be included to providesupport and/or functional properties to the SOI device. Any number ofmaterials can be used as a substrate material. Typically, the substratecan be formed of a material having desirable properties for a particularapplication. For example, in some embodiments, mechanical strength,thermal expansion, thermal conductivity, electrical resistivity, and thelike can be important. Several non-limiting examples of suitablesubstrate materials include tungsten, silicon, silicon carbide, siliconnitride, titanium carbide, titanium nitride, boron nitride, graphite,other ceramics, glass, molybdenum, zirconium, tantalum, chromium,aluminum nitride, DLC, and composites thereof. A substrate comprisingtungsten can provide exceptional mechanical support as well as lowthermal expansion. Similarly, a substrate comprising silicon can behighly compatible with incorporation into various semiconductor devicesand/or products. Although many materials can act as a suitablesubstrate, materials having a low thermal coefficient of expansion arepreferred. This is at least partially in consideration of reducingthermal expansion stresses at the interface between the substrate and anadjacent material, e.g. DLC, silicon, gallium nitride, gallium arsenide,etc.

[0051] An adynamic diamond layer 204 can also be on the substrate 202.The adynamic diamond layer can have a device surface 210 distal to thesubstrate. The adynamic diamond layer can comprise a diamond-containingmaterial. Typically, the adynamic layer is grown using a vapordeposition method, as discussed below in connection with the methods ofthe present invention. The adynamic diamond layer can have a number ofspecial properties which are advantageous for use in SOD devices.Generally, the diamond layer can have a thickness from about 10 nm toabout 100 μm, and in some cases about 100 nm to about 30 μm. Further,the diamond layer thicknesses of less than about 10 μm can be suitablefor some applications. In one specific embodiment, the diamond layer canhave a thickness from about 10 nm to less than 100 μm. Frequently, anadynamic diamond layer having a thickness of less than about 30 μm canprovide desired insulating affects, while also minimizing productiontime and costs.

[0052] An additional consideration includes the surface roughness of thedevice surface 210. More specifically, a very smooth device surface canhave a number of desirable effects. Some of these considerationsinclude: adherence of semiconductor layers thereto, improved resolutionof feature formation, improved coupling coefficients, and the like. Forexample, the methods and devices described herein focus primarily on SODdevices, exclusive of any features or semiconductor devices which can beformed thereon, subsequent to, or in combination with, the methodsdescribed herein. During fabrication of various devices, the focal depthof a light source can influence the resolution and minimum feature size,e.g., line width, etc., achievable using specific equipment. Focal depthrefers to the depth for which an image is in focus on the surface of awafer or other substrate. Thus, at differing depths, an exposed imagecan have a deteriorating focus or line edge acuity. Typical focal depthsare in the range of 1 μm to 2 μm, although ranges outside this areknown. In addition, a rough surface can interfere with this resolution,especially as the degree of surface roughness approaches the focal depthof the particular equipment used. Therefore, as surface roughness of anexposed surface is reduced, an increase in resolution and devicedensities can be achieved. In other words, in some cases, the surfaceroughness can be a limiting factor for device resolutions and densities.

[0053] In accordance with the present invention, surface roughness canbe significantly reduced without polishing expensive layers of diamondor silicon. This aspect will be discussed in more detail below inconnection with certain methods. As a result, the primary limitation toachievable resolutions can then be the equipment used instead of thewafer or materials exposed. As an example, the device surface 210 canhave a surface roughness (Ra) from about 1 nm to about 1 μm, andpreferably from about 1 nm to about 20 nm, and most preferably fromabout 1 nm to about 10 nm.

[0054] A semiconductor layer 206 can be coupled to the device surface210 of the diamond layer 204. The semiconductor layer can be directlycoupled to the device surface or can be coupled via an additional layer.The semiconductor layer can comprise any material which is suitable forforming electronic devices, semiconductor devices, or the like. Mostsemiconductors are based on silicon, gallium, indium, and germanium.However, suitable materials for the semiconductor layer can include,without limitation, silicon, silicon carbide, gallium arsenide, galliumnitride, germanium, zinc sulfide, gallium phosphide, gallium antimonide,gallium indium arsenide phosphide, aluminum gallium arsenide, galliumnitride, boron nitride, aluminum nitride, indium arsenide, indiumphosphide, indium antimonide, indium nitride, and composites thereof. Inone embodiment, the semiconductor layer can comprise silicon, siliconcarbide, gallium arsenide, gallium nitride, aluminum nitride, orcomposites of these materials. In some additional embodiments,non-silicon based devices can be formed such as those based on galliumarsenide, gallium nitride, germanium, boron nitride, aluminum nitride,indium-based materials, and composites thereof. Other semiconductormaterials which can be used include Al₂O₃, BeO, W, Mo, c-Y₂O₃,c-(Y_(0.9)La_(0.1))₂O₃, c-Al₂₃O₂₇N₅, c-MgAl₂O₄, t-MgF₂, graphite, andmixtures thereof. However, currently, most semiconductor devices aresilicon based.

[0055] Referring now to FIG. 2, the semiconductor layer 206 can becoupled to the device surface 210 using an intermediate layer 208. Theintermediate layer can provide a number of benefits, such as, but notlimited to, improved thermal expansion matching, providing improvedlattice matching for epitaxial growth, providing specific electronicproperties, thermal conduction, and the like. Non-limiting examples ofsuitable material for the intermediate layer can include aluminumnitride, chromium nitride, silicon, silicon carbide, silicon nitride,tungsten carbide, gallium nitride, tungsten carbide, boron nitride, W,Mo, Ta, Cr, and composites or alloys thereof. In some embodiments, theintermediate material can comprise aluminum nitride, chromium nitride,silicon nitride, tungsten carbide, gallium nitride, and compositesthereof. In yet another additional embodiment, the intermediate layercan comprise a material selected from the group consisting of aluminumnitride, chromium nitride, tungsten carbide, and composites thereof.Currently, the intermediate layer can be preferably aluminum nitride.Aluminum nitride can be beneficial since epitaxial growth of typicalsemiconductor materials, e.g., silicon and gallium based materials,thereon is facilitated with improved lattice matching.

[0056] Alternatively, an optional intermediate layer can comprise anelectrically conductive material. Non-limiting examples of suitableconductive materials can include copper, aluminum, tungsten, tantalum,and alloys thereof. This optional intermediate layer can be included toprovide a unique option of designing semiconductors having positive andnegative electrodes on either side of the insulating layer.

[0057] Typically, the intermediate layer can have a thickness such thatthe contours and smoothness of the adynamic layer are substantiallyunaltered. However, some variation can occur, common thicknesses canrange from about 50 nm to about 10 μm, and preferably about 400 nm toabout 5 μm, depending on the specific application and device.

[0058] Referring now to FIGS. 3A through 3D, one method for making anSOD device in accordance with the present invention is shown. FIG. 3Aillustrates a mold 220 having an interface surface 212 configured toinversely match a configuration intended for a device surface 210 of theSOI device. The mold used in the methods of the present invention can beof any material sufficient to withstand the vapor deposition and/orother layer formation processes, and allow the formation of a diamondfilm, or other intermediate layer thereon. Additionally, the mold can bedesigned to form a single or multiple SOD devices from which individualfinal SOD devices can be recovered. As a general overview of thefollowing discussion, once the adynamic diamond layer is grown, the moldcan be completely removed or only partially removed. The mold cancomprise almost any suitable material, and in some cases can comprise amaterial suitable for use as the intermediate and/or semiconductorlayers.

[0059] Although many materials can be used, the mold can comprisetungsten, silicon, titanium, chromium, zirconium, molybdenum, tantalum,manganese, carbides of these metals, ceramics, and composites or alloysthereof. However, in one aspect, the mold may be made of, orsubstantially made of, a metallic material. The metallic material may bea member selected from the group consisting of aluminum, copper,tungsten, molybdenum, tantalum, zirconium, vanadium, and chromium. Inanother embodiment, the mold may be made of, or made substantially of,non-metals, such as carbides and ceramics, including glass, oxide, andnitride materials. Examples of carbide materials include withoutlimitation, tungsten carbide (WC), silicon carbide (SiC), titaniumcarbide (TiC), zirconium carbide (ZrC), and mixtures thereof amongothers. Examples of oxide materials include without limitation, quartz(i.e. crystalline SiO₂), corundum or sapphire (i.e. Al₂O₃), LiTaO₃,LiNbO₃, ZnO, and mixtures thereof. Examples of nitride materials includewithout limitation, silicon nitride (Si₃N₄), aluminum nitride (AlN),boron nitride (BN), titanium nitride (TiN), zirconium nitride (ZrN), andmixtures thereof, among others. Examples of glass include all types ofglass including soda glass, etc. Alternatively, the mold can comprise amaterial suitable for use as a semiconductor or intermediate layer asdisclosed earlier.

[0060] The mold can be polished to form a very smooth interface surface212. Polishing the mold interface surface may be accomplished using avariety of methods known to those skilled in the art; however, use ofmicron or nano-sized diamond particles during the polishing step canalso provide a good nucleation enhancing layer for vapor deposition ofdiamond. The interface surface can be polished to a surface roughnesscorresponding to a desired surface roughness of the device surface 210.Certain non-metallic materials, such as the carbide and ceramicmaterials recited above are particularly well suited for use as a moldin the present invention because of their hardness and ability toachieve an extremely smooth interface surface. A smooth interfacesurface is particularly important when making a SOD device that requiresa smooth device surface. In many cases, the interface surface of aceramic material may be polished to have a surface roughness of lessthan about 10 μm. In other instances, the surface roughness can be lessthan about 5 μm. Depending on the device, a surface roughness of lessthan about 1 μm can provide good results. In some cases, an ultra smoothsurface can be desirable and may be less than about 20 nm. As line widthresolutions decrease, a surface roughness of less than 1 nm can also bebeneficial in providing improved exposure resolutions and imageacuities. Various methods for polishing the interface surface to achievesuch a degree of smoothness, for example with diamond or nanodiamondpowder or paste, or other diamond tools are well known to those skilledin the art.

[0061] Referring again to FIG. 3A, an adynamic diamond layer 204 can begrown on the mold 220 using a vapor deposition technique. Any number ofknown vapor deposition techniques can be used to form the adynamicdiamond layer. The most common vapor deposition techniques include CVDand PVD, although any similar method can be used if similar propertiesand results are obtained. Currently, the preferred diamond growth methodis CVD techniques such as hot filament, microwave plasma, oxyacetyleneflame, and direct current arc techniques. The reactant gases used duringsuch techniques may be any which are known in the art as useful forsafely accomplishing diamond layer fabrication using a selected CVDtechnique. However, in one aspect, the gases used in the CVD techniqueare a combination of methane and hydrogen gases. The adynamic diamondlayer can have a thickness as described above. However, in some cases aslightly thicker layer of diamond can be formed and then the growthsurface can be carefully polished to the desired thickness.

[0062] An optional nucleation enhancing layer can be formed on theinterface surface in order to improve the quality and deposition time ofthe diamond layer. Specifically, the diamond layer device surface can beformed by depositing applicable nuclei, such as diamond nuclei, on theinterface surface of a mold and then growing the nuclei into a film orlayer using a vapor deposition technique. While ceramics and othernon-metal materials are able to achieve a smooth interface surface, manyof these materials, such as oxides, are unable to nucleate diamond andretain it in place very well. Therefore, in order to overcome such adeficiency, in one aspect of the present invention, a thin nucleationenhancer layer can be coated upon the interface surface of the mold.Diamond nuclei are then placed upon the nucleation enhancer layer, andthe growth of the diamond layer proceeds via CVD as described herein.

[0063] A variety of suitable materials will be recognized by those inskilled in the art which can serve as a nucleation enhancer. In oneaspect of the present invention, the nucleation enhancer may be amaterial selected from the group consisting of metals, metal alloys,metal compounds, carbides, carbide formers, and mixtures thereof.Examples of carbide forming materials include without limitation,tungsten (W), tantalum (Ta), titanium (Ti), zirconium (Zr), chromium(Cr), molybdenum (Mo), silicon (Si), and manganese (Mn). Additionally,examples of carbides include tungsten carbide (WC), silicon carbide(SiC), titanium carbide (TiC), zirconium carbide (ZrC), and mixturesthereof among others.

[0064] The nucleation enhancer layer, when used, is a layer which isthin enough that it does not to adversely affect the transfer of theintended configuration from the interface surface to the device surface.In one aspect, the thickness of the nucleation enhancer layer may beless than about 0.1 micrometers. In another aspect, the thickness may beless than about 10 nanometers. In yet another aspect, the thickness ofthe nucleation enhancer layer is less than about 5 nanometers. In afurther aspect of the invention, the thickness of the nucleationenhancer layer is less than about 3 nanometers.

[0065] As the nucleation surface of the diamond layer can be the devicesurface of the tool, care should be taken to ensure that this surface isof the highest quality and integrity possible. Different degrees ofquality may be achieved during the vapor deposition process, as requiredby the particular device being fabricated. Those of ordinary skill inthe art will readily recognized the differing conditions and techniqueswhich produce a given degree of quality, and will be able to achievevarious degrees of quality without undue experimentation.

[0066] Various methods may be employed to increase the quality of thediamond in the nucleation surface of the diamond layer which is createdby vapor deposition techniques. For example, diamond particle qualitycan be increased by reducing the methane flow rate, and increasing thetotal gas pressure during the early phase of diamond deposition. Suchmeasures, decrease the decomposition rate of carbon, and increase theconcentration of hydrogen atoms. Thus a significantly higher percentageof the carbon will be deposited in a sp³ bonding configuration, and thequality of the diamond nuclei formed is increased. Additionally, thenucleation rate of diamond particles deposited on the diamond interfacesurface of the mold or the nucleation enhancer layer may be increased inorder to reduce the amount of interstitial space between diamondparticles. Examples of ways to increase nucleation rates include, butare not limited to: applying a negative bias in an appropriate amount,often about 100 volts, to the diamond interface surface of the mold;polishing the diamond interface surface of the mold with a fine diamondpaste or powder, which may partially remain on the interface surface;and controlling the composition of the diamond interface surface such asby ion implantation of C, Si, Cr, Mn, Ti, V, Zr, W, Mo, Ta, and the likeby PVD or PECVD. Physical vapor deposition (PVD) processes are typicallyat lower temperatures than CVD processes and in some cases can be belowabout 200° C. such as about 150° C. Other methods of increasing diamondnucleation will be readily apparent to those skilled in the art.

[0067] Polishing with diamond powder or paste is especially useful whenan ultra-smooth interface surface is desired. Further, when a finediamond paste is used to polish the interface surface, many diamondparticles may become embedded in the diamond interface surface, and canserve as seeds for increased nucleation rates. Certain metals, such asiron, nickel, cobalt, and their alloys, are known to catalyze diamondinto amorphous carbon or graphite at high temperatures (i.e. greaterthan 700° C.). Thus, by limiting the amount of such substance in thecomposition of the interface surface of the mold, the amount of diamondwhich will be catalyzed to graphite is greatly reduced, and the overallquality of the nucleation surface is increased.

[0068] In one more detailed aspect of the present invention, theinterface surface of the mold can be etched with micro-scratches toenhance nucleation. One method of introducing such micro-scratches is toimmerse the mold in an acetone bath containing suspended micron-sizediamond particles. Ultrasonic energy can then be applied to the moldand/or the fluid. Upon removal of the mold from the ultrasonic bath, aportion of the micron-sized diamonds remains on the surface as diamondgrowth seeds.

[0069] In another detailed aspect of the present invention, nucleationcan be optionally enhanced by applying an electrical current such that astrong negative bias is created at the mold. An applied voltage of about120 volts can increase nucleation density up to a million fold.

[0070] In one aspect, tungsten carbide may be used as the material forthe mold, including the diamond interface surface thereof. However, bylimiting the amount of cobalt binder contained therein to less thanabout 4% w/w, the incidence of diamond catalysis is greatly reduced.Further, it has been found that binder free tungsten carbide materialsmay be used to greatly reduce diamond catalysis. Additionally, it hasbeen found that using ultra fine or sub-micron tungsten carbide grainscreates a very smooth diamond interface surface which increases diamondnucleation. Additionally, the smooth micro-configuration of theinterface surface is imparted to the device surface of the diamondlayer.

[0071] Referring again to FIG. 3A, the device surface 210 can beproduced at the interface surface 212 of the mold 220 as the diamondlayer 204 grows. As the diamond layer grows, the growth surface becomesincreasingly rough. Once the CVD process is complete, the growth surface222 remains exposed and is typically rough compared to the devicesurface. As mentioned above, the adynamic diamond layer is notself-supporting such that if the mold were removed leaving only thediamond layer, the layer would curl or otherwise lose its intendedshape, resulting in an unsuitable surface for use in a SOD device.Typically, the thickness of the adynamic diamond layer is less thanabout 30 μm such as between about 5 μm and about 20 μm, although otherthicknesses may be suitable for particular applications.

[0072]FIG. 3B illustrates one embodiment of the present invention. Inorder to prevent deformation of the adynamic layer, a substrate 214 canbe joined to the growth surface 222 of the adynamic diamond layer 204prior to removing the mold 220 or a portion thereof in order to preventcurling of the adynamic diamond layer. In one aspect of the presentinvention, the substrate can be joined to the growth surface of theadynamic diamond layer by brazing. A variety of brazing alloys may besuitable for use in the present invention. Of particular benefit arebraze alloys which include a carbide former such as Ti, Cr, Si, Zr, Mn,and mixtures thereof. Several exemplary braze alloys include those ofAg—Cu—Ti, Ag—Cu—Sn—Ti, Ni—Cr—B—Si, Ni—Cu—Zr—Ti, Cu—Mn, and mixturesthereof. The brazing alloy may be supplied in any known form such as apowder or as a thin foil. Typical brazing temperatures are below about1000° C. such as about 900° C.

[0073] Further, the substrate can preferably comprise a material havinga thermal expansion which is comparable to that of diamond in order toprevent damage to the adynamic diamond layer upon cooling from thebrazing temperatures. Brazing to the growth surface of the diamond layerhas the added advantage in that the growth surface is rough, increasingthe strength of the braze bond between the diamond layer and thesubstrate.

[0074] In some embodiments of the present invention, it may be desirableto use a non-carbide forming material for the mold. For example, whenthe mold is a non-carbide forming material such as copper, the diamondlayer will separate from the mold upon cooling. Either before or aftercooling a braze foil may be placed on the growth surface s of theadynamic diamond layer. Subsequently, a substrate is placed against thebraze foil and the assembly is pressed together under heat, andoptionally vacuum, in order to braze the diamond layer to the substrate.In this embodiment, the mold is not attached to the diamond layer andmay be easily removed.

[0075] Alternatively, the device surface of the adynamic diamond layermay be placed against a pressing surface which may be optionally coatedwith a layer of material which prevents bonding of the pressing surfaceto the diamond layer, such as an aerosol containing boron nitride. Thebraze foil may then be placed against the growth side of the adynamicdiamond layer by carefully flattening the curved diamond layer followedby pressing the substrate against the braze foil and brazing theassembly as described above. Following joining the substrate, a portionof, or the entire mold can be removed without damaging the adynamicdiamond layer. The device surface of the diamond may be polished toremove any residual graphitic bonds, but is often not required toachieve the necessary smooth finish. Any such polishing would be minimaland would be on the order of angstroms, occasionally on the order ofnanometers, rather than microns.

[0076] Additionally, the substrate can be joined to the growth surfaceeither before or after coupling the semiconductor layer. Typically, thesubstrate can be joined before coupling of the semiconductor layer asdescribed above. However, as discussed herein, if the mold is used toform the intermediate layer or semiconductor layer, the substrate can bejoined to the growth surface subsequent to formation of thesemiconductor layer and or devices thereon. The particular choice oforder of forming individual layers can depend on processingconsiderations such as convenience, strength of the layers, pre-existingequipment layout, and the like.

[0077] In one aspect, multiple layers of diamond may be deposited overone another using vapor deposition techniques while in the mold, orafter the initial diamond layer has been formed and removed from themold to form a consolidated layer of desired thickness. In one aspect,the diamond layer may be thickened after the deposition of the initialfilm, using non-vapor techniques, as are known in the art of diamondfabrication and consolidation. In another aspect of the invention, suchthickening may take place while the initial diamond layer is still inthe mold, or after it has been removed (e.g. by dissolution in acid orKOH).

[0078] Depending on the specific embodiment the entire mold can beremoved or only a portion thereof. FIG. 3C illustrates an embodimentwherein the entire mold is removed to expose the device surface 210 ofthe adynamic diamond layer 204. The mold and/or optional nucleationenhancer layer can be separated from the diamond layer using anymechanism suitable for removing the particular substance from which themold and nucleation enhancer layer is fabricated. In one aspect of thepresent invention, the mold can be chemically removed from the diamond,such as by dissolution thereof with acid or a base solution such as KOHor by plasma etching. In another aspect, the mold can be physicallyremoved from the diamond layer, for example by grit blasting ormechanical polishing. In yet another aspect, the mold can be removedfrom the diamond layer using a heat or cold treatment, such as a furnacefor melting the mold, or liquid nitrogen for freezing and crumbling themold. In a further aspect, separation of the mold from the diamond layerdue to heating or cooling may be merely a result of different thermalexpansion properties between the mold material and the diamond material.

[0079] In accordance with the embodiment shown in FIG. 3D, asemiconductor layer 206 can be coupled to the device surface 210 of theadynamic diamond layer 204. The semiconductor layer can comprise any ofthe materials previously discussed or any other material suitable forconstruction of a particular device thereon. In another aspect of theinvention, the semiconductor material can be obtained from a singlecrystal ingot in order to control the crystal orientation, reducecrystal defects, and provide a high electromechanical coupling factor.The single crystal ingot can be typically formed from a molten liquidrather than the vapor phase. Further, the single crystal ingot typicallyhas a significantly lower defect content than crystals formed from usingvapor deposition. Also, this eliminates concerns regarding epitaxialgrowth of the semiconductor layer on diamond-containing materials whichcan be difficult.

[0080] Further, additional components can be formed upon the exposeddevice surface of the diamond layer after removal of the mold, andnucleation enhancer layer if used. The types of devices which can befabricated using the process of the present invention are any device forwhich an advantage may be found for incorporating diamond as aninsulation layer. The SOD devices of the present invention can beincorporated into various electronic devices such as, but not limitedto, logic chips, memory storage, light emitting diodes, e.g., blue LEDs,microwave generators, and other semiconductor devices. Those skilled inthe art will recognize the potential advantages of SOD devices of thepresent invention and the methods by which such devices can beincorporated into various devices such as those mentioned above or othersemiconductor devices. One significant advantage in many applicationswhich require a very smooth device surface, is that because little or nodevice surface machining is necessary after removing the mold, thenumber of variations, microcracks or fissures which are caused by suchmachining is substantially reduced, or eliminated. The reduced incidenceof variations, including microcracks on the device surface greatlyenhances the quality of the final product. Further, semiconductordevices and or features can be formed on the semiconductor layer eithersimultaneous with steps discussed herein or in separate steps accordingto known semiconductor fabrication techniques.

[0081] Alternatively, the mold can also serve as the substrate. In thiscase, the growth surface can most likely require polishing prior tocoupling the semiconductor layer.

[0082]FIGS. 4A through 4C illustrate another alternative embodimentwherein at least a portion of the mold is left in place to form a layerof the SOD device. FIG. 4A illustrates an adynamic diamond layer 204formed on the device surface 212 of a mold 220. A substrate 214 can beformed or attached as discussed previously. Alternatively, the substratecan be attached subsequent to removal of a portion of the mold.

[0083] As shown in FIG. 4B, the mold 220 can be thinned to apredetermined thickness shown by line 218. FIG. 4C illustrates the SODdevice after removal of a portion of the mold. In such instances, theportion of the mold which remains becomes an integral part of thefinished device. In order to produce a finished product under thesecircumstances, in some aspects, the outside surface of the mold may bepolished or shaped to provide a desired configuration or thicknesstherefore, if such work has not been accomplished prior to thefabrication of the diamond layer. The mold can be thinned by grinding,polishing, or chemically etching to the desired thickness.

[0084] In one aspect, the thickness of the original mold may be anythickness or configuration required to produce a specific device. Thepredetermined thickness can be greater than about 1 millimeter and insome aspects can be greater than about 5 millimeters. In an additionalaspect, the outside surface of the mold can be polished or shaped tohave a configuration required to produce a specific device. In a furtheraspect, the mold may be polished or shaped into a layer have a thicknessof less than about 1 micrometer. In another aspect, the thickness may beless than about 0.1 micrometer.

[0085] In one embodiment, the mold can comprise a material suitable foruse as the semiconductor layer. In this case, the steps of growing theadynamic diamond layer and coupling a semiconductor layer are achievedsimultaneously, i.e. the semiconductor layer is formed out of the mold.Examples of suitable mold materials which can also serve as thesemiconductor layer include, but are not limited to, silicon, siliconcarbide, gallium arsenide, gallium nitride, aluminum nitride, andcomposites thereof.

[0086] In an alternative embodiment, the intermediate layer can beprovided by providing a mold of suitable material and then removing onlyportions of the mold necessary, as discussed above, before coupling thesemiconductor layer thereto. Optionally, the intermediate layer can beformed after removal of the mold.

[0087] Additionally, the mold can be partially removed to expose atleast a portion of the device surface. Typically, the substrate can bejoined prior to removing a portion of the mold to aid in providingmechanical support. However, if only portions of the mold are removed,the remaining material of the mold can provide sufficient support inorder to allow subsequent joining of the substrate later. Thisalternative can be desirable for processing convenience or other reasonssuch as forming multiple devices in a single process. The semiconductorlayer can be coupled to the device surface by forming the semiconductorlayer on at least the exposed portions of the device surface.Alternatively, an intermediate layer can be formed on the exposedportions of the device surface and then the semiconductor layer is thenformed on the intermediate layer. In such embodiments, the semiconductorand/or intermediate layers can be formed by vapor deposition, brazing,gluing, or other known methods. In one preferred aspect, these layerscan be formed by vapor deposition.

[0088] Some SOD devices utilize a layer of intermediate material. In oneaspect of the present invention, a thin intermediate layer can be placedin contact with the smooth device surface of the diamond layer. In oneembodiment of the present invention, an intermediate layer can be placedon the interface surface prior to growing the diamond layer thereon. Insuch embodiments, the intermediate layer can comprise a material whichis suitable for nucleation and formation of diamond thereon. This canalso be enhanced by forming a nucleation enhancing layer as discussedpreviously. By depositing a thin layer of material the smooth surfaceand contours of the mold interface is retained on the depositedintermediate layer. The mold, or a portion thereof, can be removedsubsequent to the steps of growing the adynamic diamond layer and/orjoining the substrate to the growth surface.

[0089] Alternatively, an intermediate layer can be attached to thedevice surface of the diamond layer after the mold is removed.Typically, the intermediate layer can be sputtered onto the devicesurface of the diamond layer or otherwise grown. Such methods ofdepositing material on a diamond surface from a vapor phase are wellknown to those skilled in the art such as CVD, PVD, or sputtering on aheated substrate. Subsequent heat treatments can be used to producespecific crystal and lattice structure suitable for a particularembodiment.

[0090] In an alternative embodiment of the present invention, it may besuitable to use a single crystal of substantial thickness. Typicalsingle crystals are grown as ingots which are then cut for use invarious devices. Additionally, in one aspect of the present invention,the single crystals can be optionally coated with a carbide former.

[0091] However, in accordance with one aspect of the present invention,these single crystal blanks can be bonded to the device surface of thediamond layer using an ultra thin layer of bonding material. Prior tobonding with the device surface, the single crystal should be polishedto a smooth finish having a surface roughness which is comparable to thecorresponding device surface. The surface roughness will depend on theintended final device. However, in some cases, a surface roughness ofless than about one nanometer, preferably less than about 5 angstroms,can be suitable. Subsequently, an ultra thin layer of bonding materialmay be produced by forming a layer of bonding material on either thedevice surface or the smooth blank surface and then pressing the twosurfaces together in order to reduce the bonding layer thickness to lessthan about 1 micron and preferably less than about 10 nanometers (i.e.only a few molecules thick). The bonding material may comprise anorganic binder such as an epoxy or may be a reactive metal such as Ti,Si, Zr, Cr, Mo, W, Mn, or mixtures thereof. In the case of a reactivemetal, the metal may be sputtered on a either the device surface or thesmooth blank surface and then pressed against the other surface underheat and vacuum conditions. At these ultra thin thicknesses, the bondingmaterial is more stable at higher temperatures. For example, typicalepoxy binders will fail at temperatures above about 200° C.; however atultra thin thicknesses the epoxy remains strong at higher temperatures.Further, SOD devices do not require the same degree of strength as inmechanical applications. Therefore, these thin layers of bondingmaterials are suitable for SOD devices. The bonded blank can then beground and polished to any desired thickness, e.g. less than about 2 μmin the case of a SOD device.

[0092] Alternatively, the SOD devices of the present invention can beformed by providing a mold having an interface surface and growing anadynamic diamond layer on the interface surface using a vapor depositiontechnique. A semiconductor layer can be directly coupled to the growthsurface of the adynamic diamond layer. The mold can be removed, thinned,or left in place for use as the substrate. Additionally, an intermediatelayer can be formed on the growth surface. The semiconductor layer canthen be formed on the intermediate layer. Optionally, the growth surfaceof the diamond layer can be polished prior to coupling the semiconductorlayer thereto.

[0093] In order to mass produce the SOD devices of the presentinvention, the mold can be a wafer of sufficient size to producemultiple SOD devices from a single wafer precursor. Once the adynamicdiamond layer is grown, the semiconductor layer formed, and thesubstrate is joined, the larger wafer precursor can be subdivided intoindividual SOD devices. Frequently, the thermal expansion coefficientsof the diamond layer and the mold are sufficiently different to causeseparation of the layers. This is typically not a problem over an area afew millimeters across, however economic mass production generallyrequires that such components be formed on wafers and then cut from thewafers. Additionally, wafer sizes are commonly up to 6 inches and newerprocesses utilize wafer sizes of 8 or 12 inches across. Thus, thedifference in thermal expansion becomes a greater problem as the wafersize increases.

[0094] Therefore, in accordance with another aspect of the presentinvention, small grooves may be formed on the interface surface of themold. The grooves form a grid wherein each subdivided area defines asurface corresponding to a single SOD device. The grooves may be formedby etching, cutting, or any other known method. As diamond, orintermediate material, is deposited thereon the grooves act to anchorthe mold and isolate the thermal expansion differences to each gridarea. Thus, as the mold cools subsequent to the vapor depositionprocess, the contraction of the mold is limited by the diamond depositedin the grooves. For example, a single crystal piezoelectric LiNdO₃ moldcan have up to five times the thermal contraction of diamond whencooling from about 900° C. depending on the crystallographicorientation.

[0095] Although the grooves may be of any depth and width one currentembodiment utilizes grooves having a width and a depth of about 1 μm toabout 10 μm, and preferably about 5 μm. Any suitable method can be usedto form such grooves, e.g., diamond scriber, chemical etching, etc. Oneadvantage of using this method wherein the mold is only partiallyremoved (and incorporated into the final device) is that the depth ofthe groove can be chosen to correspond to the desired thickness of thesemiconductor layer or intermediate layer, although this is notrequired. For example, the mold would be made of a suitablesemiconductor material and after joining a substrate to the growthsurface of the adynamic layer, the mold can be polished until thediamond deposited in the grooves is exposed. In this embodiment, theremaining mold material is used in the final product.

[0096] Further, the degree of exposed diamond can be detected by a risein electrical resistance (as diamond is electrically insulating) acrossthe polishing surface. The electrical resistance can be measured acrossthe entire wafer in order to maintain a substantially uniform thickness.Thus, for example, if the electrical resistance increasesdisproportionately on one side of the wafer, force can be increase toincrease the polishing and removal rate at the opposite side of thewafer. As a guide, the uniform depth of the grooves helps to ensure auniform thickness of semiconductor material across the entire waferprecursor. Other components can then be attached to the semiconductormaterial and final packaging materials can be layered thereon. The finaldevices can then be separated by cutting using known techniques toproduce the final devices which may then be incorporated into variousproducts. Although dimensions can vary, SOD device dimensions cantypically have about 0.5 mm total thickness, wherein the semiconductorlayer and diamond layer are up to about 30 μm.

[0097] In another variation of the above method which utilizes groovesin the ceramic mold, a CVD diamond-passive material is deposited in thegrooves. Suitable CVD passive materials include any material on whichdiamond does not form under CVD conditions such as copper, silver, SiO₂,Al₂O₃, BN, graphite, and mixtures thereof. Copper is the currentlypreferred CVD diamond-passive material. During the CVD process diamondwill form at the interface surface but not on the CVD passive material.Following the completion of the SOD devices thereon, the CVD passivematerial may be removed by acid dissolution or mechanical force. Thisvariation of the present invention makes separating the individualdevices from the wafer precursor much less expensive since no cutting ofdiamond is required. In yet another alternative a CVD passive materialis deposited in a pattern which corresponds to individual SOD deviceswithout forming grooves in the surface of the mold.

EXAMPLES Example 1

[0098] A 100 mm diameter by 0.6 mm thick silicon wafer was polished to asurface roughness of less than 1 μm. The polished surface was thenscratched using a diamond scriber along grid lines to form scratchesabout 2 μm deep. The silicon wafer was then placed in an ultrasonic bathcontaining acetone and dispersed micron-sized diamond fines. Aftertreatment, the silicon wafer had a thin layer of micron-sized diamondparticles remaining on the polished surface. The silicon wafer was thenplaced in a hot filament CVD system having an atmosphere of 1% methaneand balance hydrogen at 40 torr. These conditions were maintained forabout 30 hours, during which a diamond film was deposited to about 30 μmin thickness. The diamond coated silicon wafer was removed from the CVDsystem. A tungsten disk having a 100 mm diameter and 0.5 mm thicknesswas brazed to the growth side of the diamond using NICROBRAZ LM at 1005°C. for 12 minutes under a vacuum at 10⁻⁵ torr. The silicon substrate wasthen ground to about 1 μm thickness using diamond deposited in thescratches as a guide to maintain uniformity of grinding. The silicon ondiamond wafer can then be further processed to form any number ofsemiconductor devices thereon.

Example 2

[0099] The same process was followed as in Example 1, except thetungsten disk is replaced by PVD sputtered tungsten.

Example 3

[0100] A 100 mm diameter by 0.6 mm thick silicon wafer was polished to asurface roughness of less than 1 μm. The silicon wafer was then placedin an ultrasonic bath containing acetone and dispersed micron-sizeddiamond fines. After treatment, the silicon wafer had a thin layer ofmicron-sized diamond particles remaining on the polished surface. Thesilicon wafer was then placed in a hot filament CVD system having anatmosphere of 1% methane and balance hydrogen at 40 torr. Theseconditions were maintained for about 30 hours, during which a diamondfilm was deposited to about 30 μm in thickness. The diamond coatedsilicon wafer was removed from the CVD system. A tungsten disk having a100 mm diameter and 0.5 mm thickness was brazed to the growth side ofthe diamond using NICROBRAZ LM at 1005° C. for 12 minutes under a vacuumat 10⁻⁵ torr. The silicon substrate was then completely removed bydissolving in a hot concentrated sodium hydroxide solution. The exposeddiamond surface was lightly polished and a 1 μm thick layer of aluminumnitride was deposited using PVD. The CVD process included an aluminumtarget in a nitrogen atmosphere under vacuum. The deposited aluminumnitride was found to align preferentially with the basal plane (0002),i.e. in parallel with a silicon surface. A semiconductor layer ofgallium nitride was then deposited to form an SOD device. The SOD wafercan then be further processed to form any number of semiconductordevices thereon.

Example 4

[0101] The same process was followed as in Example 3, except a singlecrystal of silicon was deposited on the aluminum nitride intermediatelayer in place of the gallium nitride layer.

Example 5

[0102] The same process was followed as in Example 1, except a galliumarsenide wafer was used instead of a silicon wafer. Further, a siliconwafer of the same dimensions was then brazed onto the CVD diamond. Thegallium arsenide layer was then polished to a thickness of about 5 μm.

[0103] Of course, it is to be understood that the above-describedarrangements are only illustrative of the application of the principlesof the present invention. Numerous modifications and alternativearrangements may be devised by those skilled in the art withoutdeparting from the spirit and scope of the present invention and theappended claims are intended to cover such modifications andarrangements. Thus, while the present invention has been described abovewith particularity and detail in connection with what is presentlydeemed to be the most practical and preferred embodiments of the 5invention, it will be apparent to those of ordinary skill in the artthat numerous modifications, including, but not limited to, variationsin size, materials, shape, form, function and manner of operation,assembly and use may be made without departing from the principles andconcepts set forth herein.

What is claimed is:
 1. A semiconductor-on-diamond device, comprising: a)a substrate; b) an adynamic diamond layer on the substrate having adevice surface distal to the substrate; c) a semiconductor layer coupledto the device surface of the diamond layer.
 2. The device of claim 1,wherein said semiconductor layer is coupled using an intermediate layercomprising a material selected from the group consisting of aluminumnitride, chromium nitride, silicon, silicon carbide, silicon nitride,tungsten carbide, gallium nitride, tungsten carbide, boron nitride,diamond-like carbon, tungsten, molybdenum, tantalum, chromium, andcomposites or alloys thereof.
 3. The device of claim 2, wherein saidintermediate layer comprises a material selected from the groupconsisting of aluminum nitride, chromium nitride, tungsten carbide,gallium nitride, and composites thereof.
 4. The device of claim 2,wherein said intermediate layer is aluminum nitride.
 5. The device ofclaim 2, wherein said semiconductor layer is formed directly on theintermediate layer.
 6. The device of claim 1, said device surface havinga surface roughness (Ra) from about 1 nm to about 1 μm.
 7. The device ofclaim 1, wherein said semiconductor layer is formed directly on thedevice surface of the diamond layer.
 8. The device of claim 1, whereinsaid diamond layer has a thickness from about 0.1 μm to about 30 μm. 9.The device of claim 1, wherein said semiconductor layer comprises amember selected from the group consisting of silicon, silicon carbide,gallium arsenide, gallium nitride, aluminum nitride, and compositesthereof.
 10. The device of claim 9, wherein said semiconductor layercomprises a member selected from the group consisting of silicon,gallium arsenide, gallium nitride, and composites thereof.
 11. Thedevice of claim 10, wherein said semiconductor layer comprises a memberselected from the group consisting of gallium arsenide, gallium nitride,and composites thereof.
 12. The device of claim 1, wherein the substratecomprises a member selected from the group consisting of tungsten,silicon, silicon carbide, silicon nitride, titanium carbide, titaniumnitride, boron nitride, graphite, ceramics, glass, molybdenum,zirconium, tantalum, chromium, aluminum nitride, DLC, and compositesthereof.
 13. The device of claim 12, wherein the substrate comprisestungsten.
 14. The device of claim 12, wherein the substrate comprisessilicon.
 15. A method of making a semiconductor-on-diamond (SOD) devicecomprising the steps of: a) providing a mold having an interface surfaceconfigured to inversely match a configuration intended for a devicesurface of the SOD device; b) growing an adynamic diamond layer on themold using a vapor deposition technique, said adynamic diamond layerhaving a growth surface opposite the device surface; c) removing atleast a portion of the mold; and d) coupling a semiconductor layer tothe device surface of the adynamic diamond layer.
 16. The method ofclaim 15, wherein the mold comprises a member selected from the groupconsisting of tungsten, silicon, titanium, chromium, zirconium,molybdenum, tantalum, manganese, and composites or alloys thereof. 17.The method of claim 15, further comprising the step of thinning themold.
 18. The method of claim 17, wherein step of thinning the moldforms the semiconductor layer.
 19. The method of claim 18, wherein themold comprises a material selected from the group consisting of silicon,silicon carbide, gallium arsenide, gallium nitride, aluminum nitride,and composites thereof.
 20. The method of claim 17, wherein step ofthinning the mold forms an intermediate layer.
 21. The method of claim20, wherein the mold comprises a material selected from the groupconsisting of aluminum nitride, chromium nitride, silicon, siliconcarbide, silicon nitride, tungsten carbide, and composites thereof. 22.The method of claim 20, wherein the step of coupling the semiconductorlayer is accomplished by forming the semiconductor layer on theintermediate layer.
 23. The method of claim 15, wherein the step ofremoving the mold includes exposing at least a portion of the devicesurface.
 24. The method of claim 23, wherein the step of coupling thesemiconductor layer is accomplished by forming the semiconductor layeron at least the exposed portions of the device surface.
 25. The methodof claim 23, wherein the step of coupling the semiconductor layer isaccomplished by forming an intermediate layer on the exposed portions ofthe device surface and then forming the semiconductor layer on theintermediate layer.
 26. The method of claim 25, wherein the intermediatelayer comprises a member selected from the group consisting of aluminumnitride, chromium nitride, tungsten carbide, silicon carbide, galliumnitride, and composites thereof.
 27. The method of either claim 17 or23, further comprising the step of forming an intermediate layer on theinterface surface of the mold prior to growing the adynamic diamondlayer thereon.
 28. The method of claim 15, further comprising the stepof joining a substrate to the growth surface of the adynamic diamondlayer.
 29. The method of claim 28, wherein the step of joining thesubstrate to the growth surface is accomplished by brazing with a brazealloy containing a carbide forming agent.
 30. The method of claim 28,wherein said substrate comprises a member selected from the groupconsisting of tungsten, silicon, silicon carbide, silicon nitride,titanium carbide, titanium nitride, boron nitride, graphite, ceramics,glass, molybdenum, zirconium, tantalum, chromium, aluminum nitride, DLC,and composites thereof.
 31. The method of claim 15, wherein theinterface surface has a surface roughness (Ra) of less than about 1micrometer and wherein the device surface of the diamond produced has asurface roughness (Ra) of less than about 1 micrometer.
 32. The methodof claim 31, wherein each surface roughness (Ra) is less than about 10nanometers.
 33. The method of claim 15, wherein the adynamic diamondlayer has a thickness of less than about 30 micrometers.
 34. A method ofmaking a semiconductor-on-diamond (SOD) device comprising the steps of:a) providing a mold having an interface surface; b) growing an adynamicdiamond layer on the interface surface using a vapor depositiontechnique, said adynamic diamond layer having a growth surface oppositethe interface surface; c) coupling a semiconductor layer to the growthsurface of the adynamic diamond layer.
 35. The method of claim 34,wherein the step of coupling the semiconductor layer further comprisesforming an intermediate layer on the growth surface and then forming thesemiconductor layer to the intermediate layer.
 36. The method of claim34, further comprising the step of polishing the growth surface of thediamond layer prior to coupling the semiconductor layer thereto.
 37. Themethod of claim 34, wherein the adynamic layer has a thickness fromabout 10 nm to about 100 μm.
 38. The method of claim 37, wherein theadynamic layer has a thickness from about 100 nm to about 10 μm.